Hydrogen

The first element on the periodic table. Hydrogen without any neutrons is sometimes called protium; with one neutron, deuterium; with two, tritium.

Basic Information:
| Name: Hydrogen
| Symbol: H
| Number: 1
| State at STP: Gas
| Melting / Freezing Point: 14 K
| Boiling Point: 20 K

Two hydrogen atoms and one oxygen atom make a water molecule.

Hydrogen

The first element on the periodic table. Hydrogen without any neutrons is sometimes called protium; with one neutron, deuterium; with two, tritium.

Basic Information:
| Name: Hydrogen
| Symbol: H
| Number: 1
| State at STP: Gas
| Melting / Freezing Point: 14 K
| Boiling Point: 20 K

Two hydrogen atoms and one oxygen atom make a water molecule.

Helium

The second element on the periodic table. It is a noble gas, and therefore, doesn't react to many other elements. It is also the only noble gas in the s-block.

Basic Information:
| Name: Helium
| Symbol: He
| Number: 2
| State at STP: Gas
| Boiling Point: 4 K

Helium cannot become a solid unless there is a lot of pressure.